Common Machining Mistakes

  • Published: 23 November 2019
  • This episode on, I'm talking about common machining mistakes that all beginners encounter! Exclusive videos, drawings, models & plans available on Patreon!

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    • Fowler dial bore gauge :
    • Fowler inside micrometer :
    • Starrett automatic center punch :
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    • 1-2-3 Blocks :
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  • Science and Technology Science and Technology

Comments • 240

  • Joe Pieczynski
    Joe Pieczynski  1 months back

    Hi Quinn, you had me on the edge of my seat hoping I was going to get asked to fix them. Oh well, next time. And hey...your center to center error was positioned on the 'Y' axis, yet your centerpunch error was on the 'X' axis. Hmmmmm

    • Blondihacks
      Blondihacks   1 months back

      @Joe Pieczynski His video on the Johnny Five antenna starts where this one leaves off.

      The situations in this video are very contrived, as a way to demonstrate moving punches and other things. Obviously not the way you'd actually make a part like that. You're the first person to catch that continuity error on the X/Y thing though. 😀

    • Joe Pieczynski
      Joe Pieczynski  1 months back

      @Blondihacks I like to think it was a test of who's paying attention. I enjoyed the video. Where did TOT give you a shout out?

    • Blondihacks
      Blondihacks   1 months back

      The magic of YouTube. 🤫

  • David Daniels
    David Daniels  2 days back

    I'll fess up, I've made all those mistakes and many more.

    • Lister Dave
      Lister Dave  4 days back

      @11:00 When making standard pneumatic slide plates for my hydraulic crankcase I tend to use a different method. Wherever possible I use the milling machine itself to measure rather than marking and centerpunching. I just use the smallest centre-drill (from the lathe) that will fit in the chuck and drill the center holes, using the machine's dials to move the correct amount.
      I'm not a machinist, just a hobbyist with a $800 Chinese CNC but it just seemed the logical way to do it. Besides I've never have a rocket ship blow up on launch for hydraulic failure so I can't be doing it that wrong.

      • Peter R
        Peter R  2 weeks back

        Machining Noob here, but another mistake that's easy to make is using a bad reference. For example, I just made a 3/8-24 chuck adapter for my Taig Lathe, but when I tried it out it was horribly out of alignment. So, I cut off the thread, turned it down, and tried again. And it turned out to be misaligned again. But, it was misaligned by the exact same amount at the exact same angle, despite me being much more careful this time.
        Fast forward a half hour of futzing with some indicators and it turned out that what I made was concentric to 0.01mm or better. But, my brand new Jacobs chuck was out by about 0.4mm.
        I'm still waiting on getting a replacement chuck, but at least now I know to be extra careful, and to use trustworthy references when checking my work.
        Also, Hex dies are a pain to use (even ones that are not just for thread repair) and I wish I'd known that before I got my tap and die set.

        • Ade Swash
          Ade Swash  3 weeks back

          Hi Quinn, love your videos and your presentation style, would love to see you make something, how about making a WigWag engine?

          • Ade Swash
            Ade Swash  3 weeks back

            @Blondihacks Awesome! I look forward to some 'make' vids, keep up the good work :) Ade

          • Blondihacks
            Blondihacks   3 weeks back

            You bet! I’ll be doing more making of things soon.

        • Paul Kerfoot
          Paul Kerfoot  3 weeks back

          Good video, I find an optical center punch helps a lot.

          • Ron D'vivre
            Ron D'vivre  4 weeks back


            Regarding micrometer feel;
            Grab a feeler gauge set, set the mic to 0.004” for example and pull a 0.004” feeler through the mic. Pretty good so far, eh?
            Now set the mic a half a thou under, feel what too tight feels like, set half a thou over and feel too loose, immediately return to just right to reinforce the lesson.
            Next, select the thinnest feeler gauge of your set, often it's 0.0015” or 0.002”, this one should push through the mic's anvils without buckling. Caution, if the mic is set too tight on these thinnest feelers they are subject to tears. (tears pun unintentional).
            Repeat daily or weekly until the mind/muscle interface is adequately programmed.
            Side benefit, you've also just programmed your feeler gauge 'feel'.
            Nifty innit?

            From a old mechanic hoping to pick up on some machining.

            • One Man Rifle Maker
              One Man Rifle Maker  4 weeks back

              So I looked in the machinists hand book at the required page for the metric fist shake conversation chart. Not there.
              Then I remembered that TOT And Clickspring lathe time traveled and stoped the metric system from being invented.
              So I fired up the cnc router mill and jumped into the quantum realm and using TOT radiation emanating from the YouTube black hole I got a almost perfect replacement sorted.
              It’s only off by 0.0000000001 coco pops.

              You can now find the table on page 10927. But don’t use it on a equinox or in a plural zone.
              Your welcome

              • jasoncy31
                jasoncy31  4 weeks back

                Man, I learn a lot from this channel. Thanks Quinn.

                • dfailsthemost
                  dfailsthemost  1 months back

                  Getting that micrometer feel right is tough

                  • MrCoffeypaul
                    MrCoffeypaul  1 months back

                    Great to have a female come in and show the boys how to do it, Love it!

                    • RA-75
                      RA-75  1 months back

                      Mrpete222 suggests developing venier and micrometer skills by using gauge blocks. I bought three sets of imported gauge blocks that are just as good as the name brands (verified) for general machine room use. With these you can test your skills by randomly wringing blocks and measuring to see how good you are getting. What do you think? Is mrpete222 right – I think he is!

                      • RA-75
                        RA-75  1 months back

                        Well Quinn, Mrpete222 was my spiritual guide – my machining guru – and I say this with sincerity.

                        Before buying any machine tools I spent nearly two years watching Mrpete222, Myfordboy, Keith Rucker and Abom, but mainly Mrpete222. Once I was confident that I had enough knowledge about the basics of ‘making metal chips’ I then starting buying the tools. First, I bought my lathe and then my mill along with everything else I would need based on what I had seen from the YouTube videos. I spent too much according to my children – but I now want for ‘nothin’!

                        My professional training was in chemistry and physics, and I had a lot of experience with electronics as a ham radio operator, and as a builder of communications gear. However, the Internet killed traditional Ham radio.

                      • Blondihacks
                        Blondihacks   1 months back

                        Mr. Pete is always right. 😁

                    • Robert Lark
                      Robert Lark  1 months back

                      Another great, informative video. Always look forward to your offerings. One question though. Is there a way to calibrate the thumb wheel on OD mics? I've found that some seem either looser or tighter than others. My thoughts are that using the thumb wheel will assist with repeatability but won't necessarily guarantee accuracy.

                      • FireguyNtx
                        FireguyNtx  1 months back

                        Sounds like some extra tactile safecracking stuff with the feel for the crossing on the "x" with the layout fluid. I'm not quite up to that level yet that I can feel the slight detent mark it makes.

                        • Treat Hull
                          Treat Hull  1 months back

                          I just jumped in for $10 a month on Patreon. When I thought about the value, it was a no-brainer. We had cable TV for years and with all the upsells, paid nearly $100 a month for crap. It costs a minimum of $25 to go to a stupid Hollywood movie that just leaves you shaking your head after it’s over, wondering why you did that again. So to pay a measly $10 bucks a month for something that’s real, substantive content, it’s no-brainer. I’m a Canuck and I paid $13 bucks in northern pesos and it was still a good deal. I am new hobbyist and this one video will save me $10 a month until the end of days.

                          I don’t think cable tv or the movies are any better in the States than they are here in the frozen north, so when you’re paying with US dollars it’s even better value. There’s 10 times as many people in the States as their are here, so given that Quinn got at least one Canadian (me) to sign up for Patreon today, I like to challenge 10 times as many viewers from the States to sign up to Patreon...and you’re not even paying $13.

                          Are there ten of you out there in the States who are ready to take me up on this Can-Am challenge? If think it’s a stupid idea, then explain me how this channel doesn’t provide $10 a month in knowledge. If you apprenticed in machining at Pratt & Whitney in 1955, maybe I can see your point, but otherwise....

                          (For the cynics out there who think Quinn put me up to this, she’s never met me, doesn’t know me and couldn’t pick me out in a police line-up.)

                          • Adam Comfort
                            Adam Comfort  1 months back

                            This is my first Blondihacks video I have watched, and I am just starting to look into machining. I'll be honest, though I am still not 100% confident in this, it took me until the end of the video to realize that it may not actually be common for that first part to be recognized as valve stem from a magnetic flux pump. Great video, and good information. The This Old Tony reference made me laugh, you got yourself a subscriber. lol

                            • Adam Comfort
                              Adam Comfort  1 months back

                              @Blondihacks I will check those out, thanks!

                            • Blondihacks
                              Blondihacks   1 months back

                              Thanks for watching! I have an two introductory video series on machining, if you’d like to see what it’s all about. Check out my Lathe Skills and Mill Skills playlists.

                          • noctrnalAndroid
                            noctrnalAndroid  1 months back

                            Hi, great channel, got here from a reference in the latest Uri Tuchman video. Would love to see a collaboration with him.

                            • always tinkering
                              always tinkering  2 months back

                              I'd add always wipe the part and anvils clean with a finger, not a rag because the rag could leave particles of lint. Air blow also works well to clean without the danger of adding dirt. The tensions on those ratchets can vary but that doesn't matter. The goal is to use the exact same pressure when measuring as you did when you calibrated the tool. I also agree- repeat the measurement on a different spot. On a lathe part, check both ends of the turned area to check for taper.

                              • always tinkering
                                always tinkering  2 months back

                                Metric conversion fist shake chart LOL

                                • DesmoFan
                                  DesmoFan  2 months back

                                  Laguna Seca? xD

                                  And Lordy, my old timer would've dragged me out the door and drop kicked me off the pier if I was using my calipers as a scribe O_O

                                  • Blondihacks
                                    Blondihacks   2 months back

                                    Good eye! Wondered if anyone would recognize it. As for the calipers, stay tuned for more on that. 😬

                                • Charles Balliet
                                  Charles Balliet  2 months back

                                  concise and informative, thank you!

                                  • ariesmars29
                                    ariesmars29  2 months back

                                    I wondered why the video started to remind me of someone else. Just talking hands, then the Tony joke. Do you know Chris, from clickspring and Joe Pie too? :)

                                    • Blondihacks
                                      Blondihacks   2 months back

                                      I do know Joe, as a matter of fact. 😁

                                  • frank jensen
                                    frank jensen  2 months back

                                    fuking bull shith

                                    • Gregory Carroll
                                      Gregory Carroll  2 months back

                                      Wiping your surfaces should become a subconscious action. Great video, new subscriber.

                                      • JC Mills
                                        JC Mills  2 months back

                                        Good video but a couple points to chime in on not to belittle. Putting a round in there like i think I saw when roughing a sawed block to begin trueing it up actually dates back to the civil war stone age and is not a good way to do it. Instead take a piece of aluminum about 5 inches long and relieve it down about .020 leaving a rectangular pad about the surface area of a stamp. You then simply put it like a handle with the pad near the middle of the item and clamp down on it. The rod concept in there dates back to bad information that got into text books and never was changed. The rod thing is wrong for multiple reasons including that it allows the item to pivot microscopically from the solid jaw at the top and bottom depending on direction of cut and amount of force. I will do a video since its complex. When doing the holes it seems its a bridgeport type mill where a person simply goes to the numbers--I assume you layed it out as an instructional thing.

                                        • JC Mills
                                          JC Mills  2 months back

                                          the rod thing also allows the part to pull up on one edge and crash the cutter which it can and will do. The rod thing on a rough part not milled yet is only going to contact on one edge..

                                      • Jean Roch
                                        Jean Roch  2 months back

                                        Metric fist shake LOL ! :-D

                                        • rychio1340
                                          rychio1340  2 months back

                                          At the end hand shot, I was thinking to myself, "This reminds me a lot of This Old Tony"

                                          • John Cooper
                                            John Cooper  2 months back

                                            Are you into sports car racing, also?

                                            • Blondihacks
                                              Blondihacks   2 months back

                                              I did endurance racing for several years, yep

                                          • ⵉⵜⵔⵓⵏⴰⵓⵜ
                                            ⵉⵜⵔⵓⵏⴰⵓⵜ  2 months back

                                            I wish that I could like this video twice.

                                            • Taffer9876
                                              Taffer9876  2 months back

                                              I did machining for 15 years. Nothing would burn my butt more than the new QC inspector they just hired and has never used a calipers before telling me my part it short or whatever. Never mind the flex of their muscles as they push the jaws together as hard as they can.

                                              • Robert Boll
                                                Robert Boll  2 months back

                                                Where have you been hiding? I thought I subscribed to all of the machining channels. And you are Canadian? The element of Timbits? Lol. The more techical AvE. New Patreon for you. (I stopped with him when he hit US$20k a month)

                                                • Blondihacks
                                                  Blondihacks   2 months back

                                                  Thanks very much for the supporting me! 😬

                                              • Larry Dakin
                                                Larry Dakin  2 months back

                                                Another Good practice is to check the calipers and micrometer against a calibrated block on a regular basis.

                                                • Larry Hash
                                                  Larry Hash  2 months back

                                                  "Racing is a metaphor for life" and many other gems

                                                  • MrTim3990
                                                    MrTim3990  2 months back

                                                    "Like" the Back to The Future references. Clever!

                                                    • Billy McCulloch
                                                      Billy McCulloch  2 months back

                                                      Factoring primes is my specialty. Give me any prime, I'll give you its factors. Just don't ask me to factor non-primes...

                                                      • Collin Smith
                                                        Collin Smith  2 months back

                                                        Haha. I must confess I, like many other public school grads, have always had a tough time “factoring prime numbers.” Lol. (Your comment made me laugh.)

                                                        • protator
                                                          protator  2 months back

                                                          Nah, last I've seen that ol Tony he was pretty busy massaging some life back into the MAHO and building parts for sentient robots.

                                                          • Wallace Grommet
                                                            Wallace Grommet  2 months back

                                                            Why can’t we have a laser scan micrometer and eliminate mechanical interfaces

                                                            • GunFun ZS
                                                              GunFun ZS  2 months back

                                                              Cost. Reflective surfaced. Fragility.

                                                          • Engineers Workshop
                                                            Engineers Workshop  2 months back

                                                            Great tips! By habit, wipe face of anvils before every measurement.

                                                            • Michael Lloyd
                                                              Michael Lloyd  2 months back

                                                              This video generated TWO This Old Tony videos! Well, one with another on the way? Be very careful with this. I've seen it form a rip in the continuum and translocate Clickspring. You must know where the rip is directed prior to initiating the rip. You don't want to put Chris in harms way by transporting him into Adam's shaper.

                                                              Clearly working on the valve stem from a magnetic flux pump can generate torsional instability in the continuum. That will cause brass to transition to an inter-micrometer magnetic state therefore attracting chips to the anvil. More simply put, the potential for kinetic energy increased :)

                                                              My little lathe has enough slop in it to make measurement accuracy of ± 0.01 possible. But if I "lead the lag" I can get ± .001. Ya just gotta know your limitations :o)

                                                              A large amount of MBFM (male bovine fecal matter) was used in the creation of this post.

                                                              • Misiu Kowalski
                                                                Misiu Kowalski  2 months back

                                                                I'd be curious to see how you use 2 parallels and a wire, how you setup and why you use 2 and a wire instead of 1 and a wire. Or how you clamp the wire, cause I'm taking a class and it's so hard to clamp the vise and keep the wire in there lol

                                                                • ROTTK9
                                                                  ROTTK9  2 months back

                                                                  errors happen.. keep up the good work and always improve.
                                                                  just an observation, as you have scribe lines touch the center drill enough to make the circle and double check, your eye can see if it is off and needs to be moved... never be in a hurry to get it wrong ( it's a human flaw that everybody has )

                                                                  • David Lampe
                                                                    David Lampe  2 months back

                                                                    I’m new to your channel. I’m loving your video on measuring and your honest answer to common problems with measuring.
                                                                    I have a passion for machinery and working on machine tools.
                                                                    I’m really glad you are invested in your craft.
                                                                    It’s not easy teaching measuring and how to troubleshoot when the measuring process is seemingly working properly.
                                                                    When I used to work in the machine shop we developed feel for the amount of drag on a caliper or micrometer. I’m saying that you can sense the amount of torque on a given part measurement.
                                                                    Good job keep up the lessons.

                                                                    • Mike Michelizzi
                                                                      Mike Michelizzi  2 months back

                                                                      If you're factoring primes in your head then you might want to set your sights a little higher than the machine shop floor, haha

                                                                      • Stephen Boyd
                                                                        Stephen Boyd  2 months back

                                                                        Surely having thinner jaws will give your calipers LESS easier to get the jaws crooked. If you took it to the extreme where the jaws were just points then it would be impossible to get the jaws crooked.

                                                                        • Blondihacks
                                                                          Blondihacks   2 months back

                                                                          The thinness of the jaws does not prevent you from getting crooked on the work and measuring a hypotenuse. If everything was zero friction, then your infinitely-small jaw scenario would be correct. Since friction exists, thicker jaws make it easier to feel when you’re out of square.

                                                                      • Vestjyden
                                                                        Vestjyden  2 months back

                                                                        One important thing not mentioned about lathe work is tool pressure.
                                                                        If doing several heavy cuts and one light finish cut, a change in tool pressure will make the part undersize. And yes, I have done that more than one time.
                                                                        Especially with long and thin parts, it can make a large difference.
                                                                        Always try to keep two finish passes same depth of cut and same feed.

                                                                        Another mistake is changing a worn carbide insert and the new insert cuts better and also make the part undersize.

                                                                        • Vestjyden
                                                                          Vestjyden  2 months back

                                                                          But to be fair, if turning short solid brass parts with hss tools as in the video, tool pressure is mayby not so important.

                                                                          When I did CNC lathe work for a living, it was mostly long 304 stainless thin and medium wall pipe, 10 to 45" long and not compensating for tool pressure would scrap most of the parts.

                                                                        • Chris
                                                                          Chris  2 months back

                                                                          It's about time someone said it. This is the NUMBER ONE REASON for undersized parts. I just posted a whole paragraph about it.

                                                                      • DomManInT1
                                                                        DomManInT1  2 months back

                                                                        Would love to have a video of you discussing your history. How did you get here?

                                                                        • Blondihacks
                                                                          Blondihacks   2 months back

                                                                          You’re in luck- I have just such a video. 😁 Check out the Anniversary Q&A on my channel.

                                                                      • DomManInT1
                                                                        DomManInT1  2 months back

                                                                        Biggest and most common mistake I see students/beginners make is alignment of measuring tool to the surfaces to be measured. Which you covered. Good job.